Modelling the impacts of climate change on Australian streamflow

This paper presents the likely impacts of climate change on runoff, evapotranspiration and soil moisture in the more populated and important agricultural regions of Australia. The impacts are estimated by comparing the water fluxes simulated by a hydrologic model using present climate data and greenhouse-enhanced climate scenarios predicted by general circulation models. The results indicate that changes in rainfall are amplified in runoff. In wet and temperate catchments the percentage change in runoff is about twice the percentage change in rainfall, whereas in ephemeral catchments with low runoff coefficients the percentage change in runoff can be more than four times the percentage change in rainfall. The modelling study estimates that the annual runoffs in catchments on the northeast coast and east coast of Australia could change by -5 to +15% and +/-15% respectively by the year 2030. The annual runoff in southeast Australia could decrease by up to 20%, and in Tasmania a +/-10% change in runoff by 2030 is possible. The model simulates a decrease in the annual runoff in catchments in the South Australian Gulf of up to 25% by 2030, and a change of -25% to +10% in the runoff on the southwest coast of Australia. Although there are large uncertainties in these estimates, the results show the potential for climate change to bring about runoff modifications that may require a significant planning response. Copyright (C) 2002 John Wiley Sons, Ltd.